This invention relates to shakers or separators for removing shale from drilling mud and for cleaning the mud; more particularly it relates to a mechanism for supporting and tensioning a screen of such a machine.
When drilling a well such as an oil or gas well, drilling mud is circulated through the hole, and the mud carries solids, such as pieces of shale, out of the hole. It is necessary to remove the solids from the mud before using it again, and a machine known as a shale shaker is provided for this purpose. A shaker includes one or more metal wire screens, and the mud is flowed through a screen in order to strain out the solids. The screen is normally vibrated or shaked in order to speed the flow of mud through it.
Each screen of a shaker is secured in a metal frame and is stretched tightly in the frame. In the prior art arrangement shown in FIG. 1 and described more fully hereinafter, a series of locks are provided along one side edge of the screen. The locks connect with and pull on one side edge in order to tension or stretch the screen.
While the prior art lock operates satisfactorily, it has a number of disadvantages. A number of locks are provided and they are independently operated, which requires either a number of men or an excessive amount of time to operate the locks in order to remove a screen and replace it. Since the locks are independently operated, they may not tension the screen uniformly along its length. Further, the locks are mounted along one side of the machine at a location which is rather difficult to service.
It is a general object of this invention to provide an improved tensioning and lock mechanism for a screen, which avoids the foregoing disadvantages.